Oral appliance



FIG. 1 is a front perspective view of an oral appliance showing my new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a left side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The dashed broken lines in the figures illustrate portions of the oral appliance that form no part of the claimed design. 

CLAIM The ornamental design for an oral appliance, as shown and described. 